Protein kinase C-dependent expression of type I transglutaminase mRNA in ganglioside GQ1b- and calcium-stimulated human keratinocytes.

Ganglioside GQ1b was found to induce terminal differentiation in normal epidermal keratinocytes (Yada et al. (1991) Biochem. J. 279, 665-670). In GQ1b-stimulated human keratinocytes, the increase in mRNA expression of Type I TGase preceded the increases in the TGase activity. The enhancement of its mRNA expression was inhibited when protein kinase C (PKC) was suppressed by pretreatment with an inhibitor, H-7, or down-regulation by long-term preincubation with phorbol dibutyrate. These results indicate that PKC is involved in the activation of TGase probably via gene expression of TGase mRNA in GQ1b-induced human keratinocyte differentiation. Similar results were also obtained in Ca(2+)-induced differentiation.